1. Field of the Invention
The present invention relates to a printer, more particularly to a printer which is arranged to be used with a paper feeder connected to the printer at the rear thereof, which is, for example, an apparatus for feeding single sheets of paper such as post cards one after another to a platen by means of rotation of a roller, and an apparatus for feeding, by means of sprocket wheels, a continuous length of printing paper having along its side edges a plurality of successive perforations.
2. Description of the Prior Art
Among conventional printers, one known type is arranged such that it is provided with: a platen in the middle of a frame; a carriage having a printing head, placed in front of the platen and adapted for moving along the platen; motors for driving the platen, the carriage, etc.; and a controller for driving these motors, these motors, the controller and other parts being located at the rear of the platen.
The rear end of this conventional printer is closed due to the location of the controller, etc. Single sheets or a continuous length of printing paper is necessarily fed from the upper side of the platen, led therearound and inserted into the area between the platen and the printing head. When a sheet of printing paper which is different from the kind proper to a paper feeder connected to the printer frame needs to be manually inserted, the paper feeder must be replaced. This is laborious for an operation in printing on a sheet of printing paper alone.
On one hand, when the printing paper is fed from the upper side of the platen, along the outer circumference of the platen and to the upper forward hand of the same, the printing paper is curved by 180 degrees or more. Then, the printing paper, especially in case of post cards, stays in a considerably curved shape so that it becomes hard to deal with.
The continuous length of printing paper in the form of folded layers having perforations along its side edges is placed to the rear of the printer frame or under a table on which the printer frame is mounted. Such paper has to be led above the level of the platen and then downwardly led to the platen, according to the conventional way of insertion in which the paper is fed from the upper side of the platen. As a result, a guide path of the printing paper is elongated, and the whole size of the paper feeder is disadvantageously enlarged.
The conventional printer is provided with a concave guide member which faces the platen and covers over the rear side and underside of the platen. The guide member has a paper feed roller which pressingly contacts the underside of the platen. However, this roller contacts the platen by a pressing force adapted for feeding thin and pliable paper which is most commonly used. In case of printing on a sheet of printing paper such as a post card which is thick and having high stiffness, the printing paper is outwardly stretched by virtue of its stiffness and pressingly contacts the concave guide member such that the pressing force of the roller is not enough to feed the printing paper without any retard from the rotation of the platen. Thus, the sure feeding operation has not been performed.
An ordinary paper feeder for supplying a continuous printing paper has a pair of sprocket wheels for feeding a continuous printing paper to an inlet opening of the printer. When the sprocket wheels are respectively disposed in largely distanced positions, corresponding to the breadth of the continuous printing paper, this paper sometimes lowers by its weight between the sprocket wheels. In this case, the front edge of the continuous printing paper contacts the edge of the inlet opening of the printer when the paper is fed, so that the feeding mechanism does not function well. When the front edge of the continuous printing paper floats up, being fed outwards from the sprocket wheels, it sometimes hits on the outer surface of the printer frame, thus obstructing its loading.